固井水泥石低温强度诱导纳米水化硅酸钙晶核

针对低温或表层固井水泥浆候凝时间长、水泥石早期强度低且发展慢等问题,以硝酸钙、硅酸钠、梳型聚羧酸减阻剂、聚丙烯类稳定剂为原料,采用化学沉淀法+磁力搅拌+超声分散的制备工艺提高混合效率,制得水泥石低温强度诱导晶核(LTI)。通过透射电镜观察LTI的微观形貌、分析其元素组成,研究了其对水泥浆低温稠化性能和静胶凝过渡时间、水泥石低温强度发展的影响。结果表明,LTI的基本单元结构为堆叠的类锡箔状和絮片状,伴有少量棒状和规则方形晶体,尺寸为100~200 nm,周围延伸出类纤维状物质,比表面积较大。LTI借助自身模板成核作用促进水泥水化进程,降低堆积产物成核势垒,促使低温稠化曲线由爬坡向直角转变,可在10℃下将稠化时间之比控制在0.47以内。LTI可诱导水泥石早期强度快速发展,随LTI掺量增加、温度升高,水泥石低温抗压强度增大。在20℃下,掺有1.5%、5.0%LTI水泥石的24 h抗压强度分别提高89.1%、257.8%;在30℃下,掺有1.5%、5.0%LTI水泥石的6 h抗压强度分别为4.1、6.5 MPa,相比于刚成型的净浆水泥石,抗压强度实现跨越式发展。掺有LTI的水泥浆在30℃下的静胶凝过渡时间可由78 min缩短至18 min,有助于提高水泥浆的防窜性能。纳米水化硅酸钙晶核LTI可缩短低温浅层或高寒区域油气井建井周期、提高固井质量。

地铁车站步行交通网络引导标识诱导强度设计

随着我国城市交通的快速发展,城市轨道交通尤其是地铁依靠其客运能力强、准时高效等优点吸引了大量的出行者,成为城市交通网络中不可或缺的组成部分。但是,由于乘客对地铁车站复杂环境不熟悉,站内乘客分布不均衡,导致客流走行时间和关键节点(如闸机、楼扶梯)排队等待时间较长。而引导标识能够将车站走行路径、节点位置等信息传递给乘客,在地铁车站运营中发挥着重要导向和辅助疏散的作用。提出人们在寻路过程中,最主要依靠标识导向系统。因此,合理的引导标识设计能帮助乘客快速顺利地了解车站空间结构和走行路径。

判断取代基相对诱导效应强度的新方法——Ⅰ取代基中与甲基碳原子相连原子不具有不饱和键的情况

以CH4为母体,甲烷1个氢原子被取代基R取代生成的CH3R为模型,计算CH3R中甲基碳原子化学位移与甲烷碳原子化学位移的差值Δδ以及CH3R中甲基碳原子净电荷值与甲烷碳原子净电荷的差值ΔQ,将其作为判断基团相对氢原子诱导效应强度的新方法.研究结果表明,当取代基中与甲基碳原子相连原子不具有不饱和键时,2种计算结果具有紧密的相关性.就本文所列基团而言,由这2种新方法得到的相对诱导效应强弱与已有的化学规律甚为吻合.

不同诱导强度对短跑运动员后激活增强效应的影响

目的:探讨后激活增强效应(PAP)最佳动态诱导强度。方法:对8名短跑运动员分别进行11RM、8RM、4RM和1RM的杠铃深蹲诱导;将4种强度诱导后的下蹲跳(CMJ)高度、地面垂直反作用力(VGRF)、峰值功率输出(PPO)和股直肌、股内侧肌、股外侧肌的积分机电(IEMG)值在不同恢复时刻下的数据进行对比分析。结果:CMJ高度、VGRF和PPO在11RM诱导后8min时显著增长(P<0.05);在8RM和4RM诱导后4min~12min时显著增长(P<0.05);在1RM诱导后8min~12min时显著增长(P<0.05)。股直肌和股外侧肌IEMG值在11RM、8RM、4RM和1RM诱导后8min时显著增长(P<0.05);股内侧肌的IEMG值在11RM诱导后8min时显著增长(P<0.05);在8RM、4RM和1RM诱导后12min时显著增长(P<0.05)。结论:8RM是诱导短跑运动员PAP的最佳强度。

孟加拉国农业利用强度增加、土地利用/覆盖变化和土地退化(英文)

在实地采访、地块土地利用/覆盖调查和1 260个土样的收集和实验室分析等野外工作的基础上,对比分析了1984—1985年和2003—2004年265个家户的人口、农业系统、土地利用和土壤质量数据,研究了孟加拉国6个村庄农业诱导强度增强对土地和土壤质量的影响。1984—2004年家户和土质数据的百分比变化用来构建诱导强度增强模型和土地退化模型中的统计变量和土地退化指标。结果表明:研究区种植强度和土地生产力的增加主要是由于低压泵灌溉的普及,化肥和杀虫剂的使用以及水稻、蔬菜和虾生产的多元化高产。诱导强度增强模型可以解释研究区81%的种植强度增量和73%的土地生产力增量。人口压力和市场驱动也诱发了农业利用强度的增加;环境约束起到了一定制约作用;低压泵灌溉等应对干旱的技术也对农业增产有一定贡献。然而动力耕作机、低压泵灌溉和化学物质的持续利用再加上除草性水稻、蔬菜和虾的频繁耕作和养殖已经导致土壤结构、质地和化学属性的退化,生产力也有所降低。利用强度越大的土地退化现象越严重,生产力下降得也更多。土地的不断退化将有可能会引发孟加拉国的马尔萨斯危机。

全亲水性嵌段共聚物及其超分子自组装

本文介绍了全亲水性嵌段共聚物(DHBCs)的定义与特点。根据不同的环境敏感自组装机理,分类详述了不同DHBCs的结构及其超分子自组装行为,并探讨了相应的应用现状与前景。

蚯蚓活动和秸秆施用方式对土壤生物学性质的动态影响

通过实验室短期培养研究接种蚯蚓和有机物不同施用方式(混施与表施)对土壤微生物类群、土壤微生物量以及呼吸强度等土壤生物学性质的影响。结果表明,接种蚯蚓对土壤可培养酵母菌、细菌数量和土壤底物诱导呼吸强度有明显促进作用。最高增幅分别达到相应未接种蚯蚓处理的5.18,8.88,2.50倍。蚯蚓活动对土壤微生物量及真菌数量的影响受到秸秆施用的影响:在混施和不施秸秆的处理(SRME、SE)中显著抑制丝状真菌数量;在混施秸秆处理中蚯蚓活动降低了SMBC含量。秸秆的施用方式对土壤微生物性状也有较大影响。混施秸秆处理中,土壤酵母菌、细菌数量、土壤微生物量和土壤呼吸强度增加也最为明显,而丝状真菌数量的增加幅度却不如表施秸秆处理。各处理土壤微生物量碳随时间变化趋势比较一致,呈现先降(第4周)后增的变化趋势,其他测定项目没有一致的随时间变化的规律。方差分析表明秸秆施用对土壤微生物量氮和可培养微生物数量变化的贡献最大,分别达到96.5%(SMBN)、77.9%(细菌)、69.4%(酵母菌)和85.3%(丝状真菌)。并且时间、秸秆和蚯蚓因子间存在强烈交互作用。

血栓弹力图对经皮冠状动脉介入治疗患者预后的预测作用

目的评估经皮冠状动脉介入治疗（PCI）患者术后血栓弹力图（TEG）指标对其预后的预测作用。方法收集115例PCI患者资料,根据其TEG报告中二磷酸腺苷（ADP）诱导的最大血块强度（MA-ADP）将患者分为MA-MDP〈50 mm组和≥50 mm组,随访观测其1年后心血管不良事件和支架再梗死及再狭窄的发生率。结果根据MA-ADP分组的2组患者的临床基本情况差异无统计学意义（P〉0.05）。Logistic回归分析显示MA-ADP是PCI术后患者心血管不良事件复发风险的危险因素[OR=3.547（95%CI：1.103-11.412）,P=0.034]。与MA-ADP正常（〈50 mm）的患者相比,MA-ADP升高（≥50 mm）的患者的心血管不良事件和支架内再梗死的发生率均明显升高（P均〈0.05）。结论 MA-ADP对PCI术后患者的预后有预测作用,MA-ADP=50 mm可作为PCI术后患者心血管不良事件复发风险的判断切点。

Relationship between ADP-induced platelet-fibrin clot strength and anti-platelet responsiveness in ticagrelor treated ACS patients

Background Ticagrelor provides enhanced antiplatelet efficacy but increased risk of bleeding and dyspnea. This study aimed to display the relationship between ADP-induced platelet-fibrin clot strength （MAADP） and clinical outcomes in acute coronary syndrome （ACS） patients treated by ticagrelor. Methods Consecutive Chinese-Han patients with ACS who received maintenance dose ofticagrelor on top of aspirin were recruited. After 5-day ticagrelor maintenance treatment, MAADP measured by thrombelastography （TEG） were recorded for the evaluation of ticagrelor anti-platelet reactivity. Pre-specified cutoffs of MAADP 〉 47 mm for high on-treatment platelet reactivity （HTPR） and MAADP 〈 31 mm for low on-treatment platelet reactivity （LTPR） were applied for evaluation. The occurrences of primary ischemic cardiovascular events （including a composite of cardiac death, non-fatal myocardial infarction and stroke）, the Thrombolysis in Myocardial Infarction （TIMI） defined bleeding events, and ticagrelor related dyspnea were recorded after a follow-up of three months. Results Overall, 176 ACS patients （Male： 79.55%, Age： 59.91 ±10.54 years） under ticagrelor maintenance treatment were recruited. The value of MAADP ranged from 4.80% to 72.90% （21.27% ± 12.07% on average）, with the distribution higher skewed towards the lower values. Using the pre-specific cutoffs for HTPR and LTPR, seven patients （3.98%） were identified as HTPR and 144 patients （81.82%） as LTPR. After a follow-up of three months in 172 patients, major cardiovascular events occurred in no patient, but TIMI bleeding events in 81 （47.09%） with major bleedings in three patients. All patients with major bleedings were classified as LTPR. Ticagrelor related dyspnea occurred in 31 （18.02%） patients, with 30 （21.28%） classified as LTPR and no one as HTPR （P = 0.02）. Conclusions In ticagrelor treated ACS patients, MAADP measured by TEG might be valuable for the prediction of major bleeding and ticagrelor related dyspnea. Due to the small number of patients with HTPR after ticagrelor maintenance treatment, larger scale study should be warranted to verify the relationship between MAADP defined HTPR and ticagrelor related ischemic events.

预激活增强效应对爆发力的影响及应用研究进展

预激活增强效应可短时间内提升短跑、跳跃、投掷等爆发性项目运动员的运动表现,但其影响因素较多,最佳诱导方案尚无明确定论。通过梳理预激活增强效应和爆发力相关的文献,对其生理机制、影响因素、在运动项目中的应用等进行梳理,分析应用预激活增强效应时应注意的因素,为相关研究提供理论基础。

Experimental Evaluation of the Post-ultimate Strength Behavior of a Ship＇s Hull Girder in Waves

Experimental investigations into the collapse behavior of a box-shape hull girder subjected to extreme wave-induced loads are presented.The experiment was performed using a scaled model in a tank.In the middle of the scaled model,sacrificial specimens with circular pillar and trough shapes which respectively show different bending moment-displacement characteristics were mounted to compare the dynamic collapse characteristics of the hull girder in waves.The specimens were designed by using finite element(FE)-analysis.Prior to the tank tests,static four-point-bending tests were conducted to detect the load-carrying capacity of the hull girder.It was shown that the load-carrying capacity of a ship including reduction of the capacity after the ultimate strength can be reproduced experimentally by employing the trough type specimens.Tank tests using these specimens were performed under a focused wave in which the hull girder collapses under once and repetitive focused waves.It was shown from the multiple collapse tests that the increase rate of collapse becomes higher once the load-carrying capacity enters the reduction path while the increase rate is lower before reaching the ultimate strength.

Numerical simulation for propagation characteristics of shock wave and gas flow induced by outburst intensity

In order to analyze the propagation characteristics of shock wave and gas flow induced by outburst intensity, the governing equations of shock wave and gas flow propagation were put forward, and the numerical simulation boundary condition was obtained based on outburst characteristics. The propagation characteristics of shock wave and gas flow were simulated by Fluent software, and the simulation results were verified by experiments. The results show that air shock wave is formed due to air medium compressed by the transient high pressure gas which rapidly expands in the roadway; the shock wave and gas flow with high velocity are formed behind the shock wave front, which significantly decays due to limiting effect of the roadway wall. The attenuation degree is greater in the early stage than that in the late stage, and the velocity of gas convection transport is lower than the speed of the shock wave.The greater the outburst intensity is, the greater the pressure of the shock wave front is, and the higher the speed of the shock wave and gas flow is.

Simulation of thermal field induced by concave spherical transducer in multi-layer media

High intensity focused ultrasound(HIFU)therapy is an effective method in clinical treatment of tumors,in order to explore the bio-heat conduction mechanism of in multi-layer media by concave spherical transducer,temperature field induced by this kind of transducer in multi-layer media will be simulated through solving Pennes equation with finite difference method,and the influence of initial sound pressure,absorption coefficient,and thickness of different layers of biological tissue as well as thermal conductivity parameter on sound focus and temperature distribution will be analyzed,respectively.The results show that the temperature in focus area increases faster while the initial sound pressure and thermal conductivity increase.The absorption coefficient is smaller,the ultrasound intensity in the focus area is bigger,and the size of the focus area is increasing.When the thicknesses of different layers of tissue change,the focus position changes slightly,but the sound intensity of the focus area will change obviously.The temperature in focus area will rise quickly before reaching a threshold,and then the temperature will keep in the threshold range.

Induction and cultivation of cloned filaments of Polysiphonia urceolata(Rhodomelaceae,Rhodophyta)

A filamentous clone ofPolysiphonia urceolata was regenerated from segments cut from the fronds of gametophytes. Unlike wild thalli with short virgate branchlets, the clone was filamentous with few branches. Many transparent trichoblasts arose from pericentral cells during the induction culture, but these were seldom observed during normal growth. The trichoblasts were uniseriate, often colorless, and formed lobed rhizoids rapidly when they came into contact with solid substrates. In addition to morphological characteristics, the photosynthetic properties and growth conditions of the clone differed from those of the mother plant. Cross-gradient light and temperature culture experiments revealed that the most favorable conditions for culture of the filamentous clone were 22℃ and 95-120 gE/（m2-s） light intensity. The photosynthetic light saturation value for filaments was approx. 100 gE/（m2.s）, which is far lower than that of wild thalli. These results could be used to develop techniques for mass cultures of P. urceolata in photobioreactors for production of seed stock or bioactive products.

An ultrahigh strength steel produced through deformation-induced ferrite transformation and Q&P process

In this work,DIFT technology and Q&P process were combined in order to introduce ultrafine-grained ferrite into the matrix of martensite and retained austenite to develop a new kind of advanced high strength steel,and two kinds of steels were investigated by this novel combined process.The newly designed process resulted in a sophisticated microstructure of a large amount of ferrite(about 5 m in diameter),martensite and a considerable amount of retained austenite for TRIP 780 steel.The ultimate tensile strength can reach about 1200 MPa with elongation above 16% for TRIP 780,that is much higher than the one solely treated by Q&P process.Tensile tests showed that both steels with the novel combined process achieved a good combination of strength and ductility,indicating that the new process is promising for the new generation of advanced high strength steels.

冠心病介入术后性别对双联抗血小板治疗患者血小板反应性的影响

目的明确对于行经皮冠状动脉介入术(percutaneous coronary intervention,PCI)、服用双联抗血小板药物的冠心病患者血小板的反应性是否具有性别差异及对长期预后的影响。方法本研究纳入2013年1月至2013年12月于阜外医院行PCI且有术后12~72 h血栓弹力图检测结果的冠心病患者4606例,男3536例,女1070例。主要研究终点为2年主要不良心脑血管事件(major adverse cardiovascular and cerebrovascular events,MACCE:死亡、心肌梗死、靶血管或靶病变血运重建、脑卒中)及支架内血栓、大出血事件。结果通过对血栓弹力图的分析显示:男性、女性患者的花生四烯酸(arachidonic acid,AA)抑制率相似(81.0%±27.7%vs 79.7%±30.5%,P=0.178);男性二磷酸腺苷(adenosine diphosphate,ADP)抑制率高于女性(49.6%±31.2%vs 37.9%±31.2%,P<0.001);男性的二磷酸腺苷诱导的血小板纤维蛋白凝块强度(adenosine diphosphate-induced platelet-fibrin clot strength,MAADP)较女性更低[(32.6±17.1)mm vs(41.6±18.1)mm,P<0.001]。2年随访显示,男性、女性患者的MACCE发生率差异无显著性(8.5%vs 7.9%,P=0.377)。各单一主要终点事件中,男性患者死亡(1.2%vs 0.8%,P=0.045)及靶血管或靶病变血运重建(8.9%vs 6.4%,P=0.021)的发生率高于女性;其余单一主要终点事件无显著性差异。COX回归模型分析显示,MAADP并非MACCE及各单一主要终点事件的独立预测因素。结论2年随访显示,男性患者死亡及靶血管或靶病变血运重建的发生率高于女性,但MACCE发生率差异无显著性;MAADP并非是MACCE及各单一主要终点事件的独立预测因素。

冠心病介入术后女性患者不同的MAADP对抗栓治疗有效性和安全性的影响

目的对于行经皮冠状动脉介入术(percutaneous coronary intervention,PCI)、服用双联抗血小板药物的女性冠心病患者,评估不同的二磷酸腺苷诱导的血小板纤维蛋白凝块强度(adenosine diphosphate-induced platelet-fibrin clot strength,MAADP)对抗栓治疗有效性和安全性的影响。方法本研究纳入2013年1月至12月于阜外医院行PCI且有术后12~72 h血栓弹力图检测结果的女性冠心病患者1070例,分为MAADP<31mm、31mm≤MAADP≤47mm、MAADP>47mm三组。缺血性主要终点为死亡,缺血性次要终点为心肌梗死,出血终点为BARC3、5型。结果通过2年的随访,三组的缺血性主要终点、次要终点及出血终点均差异无显著性(P>0.05),Cox分析显示,MAADP并非是缺血及出血事件的独立预测因素。结论对于行PCI治疗的女性冠心病患者,不同的MAADP对抗栓疗效和安全性均差异无显著性。

Enhancement of pacemaker induced stochastic resonance by an autapse in a scale-free neuronal network

An autapse is an unusual synapse that occurs between the axon and the soma of the same neuron. Mathematically, it can be described as a self-delayed feedback loop that is defined by a specific time-delay and the so-called autaptic coupling strength. Recently, the role and function of autapses within the nervous system has been studied extensively. Here, we extend the scope of theoretical research by investigating the effects of an autapse on the transmission of a weak localized pacemaker activity in a scale-free neuronal network. Our results reveal that by mediating the spiking activity of the pacemaker neuron, an autapse increases the propagation of its rhythm across the whole network, if only the autaptic time delay and the autaptic coupling strength are properly adjusted. We show that the autapse-induced enhancement of the transmission of pacemaker activity occurs only when the autaptic time delay is close to an integer multiple of the intrinsic oscillation time of the neurons that form the network. In particular, we demonstrate the emergence of multiple resonances involving the weak signal, the intrinsic oscillations, and the time scale that is dictated by the autapse. Interestingly, we also show that the enhancement of the pacemaker rhythm across the network is the strongest if the degree of the pacemaker neuron is lowest. This is because the dissipation of the localized rhythm is contained to the few directly linked neurons, and only afterwards, through the secondary neurons, it propagates further. If the pacemaker neuron has a high degree, then its rhythm is simply too weak to excite all the neighboring neurons, and propagation therefore fails.

Meandering Spiral Waves Induced by Time-Periodic Coupling Strength

Effects of time-periodic coupling strength （TPCS） on spiral waves dynamics are studied by numerical computations and mathematical analyses. We find that meandering or drifting spirals waves, which are not observed for the case of constant coupling strength, can be induced by TPCS. In particular, a transition between outward petal and inward petal meandering spirals is observed when the period of TPCS is varied. These two types of meandering spirals are separated by a drifting spiral, which can be induced by TPCS when the period of TPCS is very close to that of rigidly rotating spiral. Similar results can be obtained if the coupling strength is modulated by a rectangle wave. Furthermore, a kinetic model for spiral movement suggested by Diet al., [Phys. Rev. E 85 （2012） 046216] is applied for explaining the above findings. The theoretical results are in good qualitative agreement with numerical simulations.

不同的MA_(ADP)对抗栓治疗有效性和安全性的影响

目的对于行经皮冠状动脉介入术(percutaneous coronary intervention,PCI)、服用双联抗血小板药物的冠状动脉性心脏病(简称"冠心病")患者,评估不同的二磷酸腺苷诱导的血小板纤维蛋白凝块强度(adenosine diphosphate-induced platelet-fibrin clot strength,MA_(ADP))对抗栓治疗有效性和安全性的影响。方法本研究纳入2013年1月至2013年12月于阜外医院行PCI且有术后12~72 h血栓弹力图检测结果的冠心病患者4606例,分为MA_(ADP)<31mm(n=1871)、31mm≤MA_(ADP)≤47mm(n=1407)、MA_(ADP)>47mm(n=1328)三组。主要研究终点为2年主要不良心脑血管事件(major adverse cardiovascular and cerebrovascular events,MACCE:包括死亡、心肌梗死、靶血管或靶病变血运重建、脑卒中)及支架内血栓、大出血事件(BARC 3型和5型)。结果通过2年的随访,三组的MACCE及各单一主要终点事件包括死亡、心肌梗死、靶血管或靶病变血运重建、脑卒中和支架内血栓、大出血等差异均无显著性(P>0.05),Cox分析包括亚组结果显示,MA_(ADP)并非是MACCE及各单一主要终点事件的独立预测因素。结论对于行PCI治疗的冠心病患者,通过2年的随访,不同MA_(ADP)对抗栓治疗的有效性和安全性的影响均无显著性差异。